Apparatus for electroplating workpieces including means to vary the position of the workpieces

ABSTRACT

An apparatus for electroplating wherein cathode means are provided to mount a plurality of articles to be plated, there being a mechanism for pressing said articles to be plated to the surfaces of said cathode means during the period of supply of current and a rotating mechanism to vary the position of the articles to which current is supplies while at the same time the supply of current is stopped, the pressing mechanism and the rotating mechanism being connected to an interlocking mechanism so that the supply of current is stopped and the pressure of the pressing mechanism is released before activation of the rotating mechanism.

July 11, 1973 A WA ET AL 3,746,633

APPARATUS FOR ELECTROPLATlNG WORKPIEZCES .LNCLUUING MEANS TO VARY THEPOST'TION OF'THE WORKP'IECES Filed Marcn 26, 1971 2 Sheets-Sheet 1 FIG.I

July 17, 1973 AKlRA MIYATO ET AL 3,746,633

APPARATUS FOR ELECTROPLATING WORKPIECES INCLUDING MEANS TO VARY THEPOSITION OF THE WORKPIECES Filed Maren 26, 1971 2 Sheets-Sheet 2 UnitedStates Patent 3 746,633 APPARATUS FGR E LECTROPLATING WGRK- PIECESINCLUDENG MEANS TO VARY THE PQSHTION OF THE WORKPIECES Akira Miyato,Hideyo Okubo, Chikayoshi Tornita, Akio U.S. Cl. 204-231 Claims ABSTRACTOF THE DISCLOSURE An apparatus for electroplating wherein cathode meansare provided to mount a plurality of articles to be plated, there beinga mechanism for pressing said articles to be plated to the surfaces ofsaid cathode means during the period of supply of current and a rotatingmechanism to vary the position of the articles to which current issupplied while at the same time the supply of current is stopped, thepressing mechanism and the rotating mechanism being connected to aninterlocking mechanism so that the supply of current is stopped and thepressure of the pressing mechanism is released before activation of therotating mechanism.

The present invention relates to an apparatus for forming a uniform andsturdy film electroplated on a surface of an article. The article may bea cylindrically-shaped article of various lengths such as a fastener, abolt, a nail and the like.

In the prior art, a barrel type apparatus is used or electroplating,with an aqueous solution, such cylindrically-shaped small articles. Anelectroplating apparatus of a barrel type, however, has drawbacks; e.g.,when applied to fused salt electroplating by electrolysis, theelectrical resistance at the point contact of an article or articles tobe plated and a cathode or the mutual point contact of articles to beplated is so unstable and great that the area in the region of a partthrough which current has been supplied remains defectively plated aftercompletion of plating. The article thus electroplated has a poordurability as a whole. It is a known fact from the past experiments bythe inventors of this invention that said electroplating apparatus of abarrel type has numerous problems in fused salt electroplating byelectrolysis.

SUMMARY OF THE INVENTION The present invention relates to an apparatusfor use in electroplating articles, in which a pressing mechanism isprovided to connect articles to be plated firmly to a cathode in aplating bath, and in addition to said pressing mechanism, a rotatingmechanism to rotate articles to be plated is provided. The rotatingmechanism is brought into action at predetermined intervals when thepressure of the pressing mechanism is nil. Thus, articles to be platedare rotated to change the parts in contact with the cathode to whichcurrent is supplied within a short period of time. A supplemental anodemay be provided in addition to said two mechanisms.

The present invention will now be described in more detail withreference to the accompanying drawings in which:

FIG. 1 is a front view of an apparatus embodying the present invention;

FIG. 2 is a side-sectional view thereof;

FIG. 3 is a partially enlarged view of the part A in FIG. 1; and

ice

FIG. 4 is a partially enlarged view of the part B in FIG. 2.

'In the drawings, a cathodic conductor 2 carrying a plurality ofarticles to be plated such as fasteners, bolts, nails and the like issupported in a plating bath 6 through a supporter 5 freely andsuspendably fixed to a bracket 4 on a lid 28 of a plating vessel 3. Theparts '7 mounting the articles to be plated have a wave shape, thevariable number of articles 1 to be plated being mounted within therecesses or troughs so formed. In this embodiment of the presentinvention, two cathodic conductors 2 and 2' are arranged in parallel ina vertical direction in the drawings as if supporting both ends ofarticles to be plated (see FJG. 2). The number of said cathodicconductors in parallel is proportionate to the size of a plating vessel3 and may be optionally increased. On the other hand, anodes 8 as shownin FIG. 2 are arranged on the upper portions of both ends and in thelower portion at the centre of the articles 1 to be plated and are fixedto a lid 28 so as to be immersed in a plating bath in order to provide aplating film having a uniform thickness. Further, supplemental anodes 9may be fixed to a bracket if so required. The ends of article 1 to beplated often have indented parts. The supplemental anodes 9 cause aremarkably efiicient electroplating treatment on the indented parts. Itis preferable to arrange a tip of a supplemental anode '9 adjacent anarticle to be plated with a very small distance between the two with theextreme tip of said supplemental anode extending beyond insulation 10.The arrangement of said supplemental anodes *9 is an optional butsubstantial feature of the present invention.

Parts 7 of the cathodic conductors carrying articles 1 to be plated actas the parts to which current is supplied, said parts being partiallycovered with insulation 11 such as Teflon or the like. When the partsnot covered with Teflon and the like are defined to the parts 7 andcontacting parts with the articles to be plated, said parts have theoperational advantage that unnecessary current is not supplied betweenthe parts 7 and the articles to be plated (refer to FIG. 3). In thisembodiment of the present invention, only one part (as in FIG. 3) isexposed. Said part is a part where current is supplied and not plated,so that it should preferably be as small as possible.

The parts 7 of a cathode where current is supplied are placedhorizontally in a plating bath, a pressing mechanism 12 being activatedtoward articles 1 to be plated whose ends are sustained therebetween.The pressing mechanism presses the articles 1 to be plated to theexposed part of a cathodic part where current is supplied to maintain afirm contact during the supply period for current. The pressingmechanism is not limited to the one illustrated in the drawings.However, as shown in the drawings the pressing mechanism 12 usesresilient rods 14 elongated to a letter J-shape, each rod 14 includes apiano wire 13 sheathed in a Teflon tube 26 and a glass tube 27 providedat the pressing part. The pressing mechanism is located at parts markedC in FIG. 1. The position of the dotted line shown in FIG. 3 is theposition of a pressing part when articles to be plated are not mountedon a cathodic conductor. A pressing part is so constructed that when apressure is applied to the articles to be plated utilizing constantelasticity it will be placed on the solid line illustrated in FIG. 3. Itis also possible to arrange a magnet (not shown in the drawings) beneatha cathode and activate the magnetism to attract and firmly contactarticles to be plated on a surface of the cathode.

As shown in FIGS. 1 and 2, a rotating mechanism 15 to vary the positionsof the articles 1 to be plated in relation to the cathode is providedcorresponding to the pressing mechanism 12. The mechanism 15 includes aglass rod 16 arranged in parallel with the horizontal point of thecathodic conductor, both ends of said glass rod being supported bysupporting rods 17 and 17, so as to be able to rotate momentarily all ofthe plurality of articles to be plated mounted in the horizontaldirection. The glass rods are rotated along the loci X and X shown bydotted circles. When the connecting face 18 of said glass rods 16 is soslanted as 18 in FIG. 2, articles 1 to be plated whose indented endparts come close to the supplemental anodes 9 are caused to rotate undera preferable condition.

Both pressing and rotating mechanisms 12 and 15 aforementioned are soarranged that upon completion of the former action the latter action isstarted by means of an interlocking mechanism 19. The interlockingmechanism 19 may be a conventionally known link mechanism. In theembodiment shown, a crank shaft 20 is employed and is so arranged thatwhen a crank part 21 is rotated by a suitable motor not shown in thedrawings, both pressing and rotating mechanisms 12 and 15 areinterlocked by means of a pin 29. For this reason, the upper end of arod 14 of the pressing mechanism 12 and supporting rods 17 and 17' ofthe rotating mechanism 15 are connected to the identical crank part 21of the crank shaft. 22 denotes a shaft pin thereof, and 23 a chainengaging each shaft, respectively. As shown in FIG. 2, a receivingmember 24 maintains a horizontal rod 25 and acts to prevent articles 1to be plated from deviating from the predetermined position of acathodic part where current is supplied. The horizontal rod 25 is freelyattachable to and removable from the receiving member 24 and enablesarticles to be plated to be easily placed in and removed from a cathodicconductor having a wave shape.

The action and operation of the novel apparatus for electroplatingcomprising such a structure as aforementioned will now be described.Articles 1 to be plated are mounted on the parts 7 in the troughs of thewavy shape of the cathode 2 immersed in the plating bath 6 by a propermeans. The supplemental anodes 9 are preliminarily so set as to beplaced in a predetermined position of the indented part at the ends ofarticles to be plated. At this time, the pressing mechanism 12 of thearticles to be plated is so placed as not to press the articles to beplated. Then the crank shaft 20 is rotated to press the articles to beplated by means of rods 14 of the pressing mechanism 12 so as to causethe articles 1 to be plated to come into firm contact with the cathodicpart where current is supplied 7 (refer to FIG. 3). The terminals fromthe power supply required for electroplating are, of course,preliminarily connected to the cathodic conductor and the anode,respectively. During the plating process, a timer is used so that therotating mechanism 15, which changes the position of the parts to whichcurrent is supplied, is activated to repeat the passage of current androtation after a predetermined period of time. In the example inaccordance with the present invention after the current is supplied for16 seconds in a stationary state, crank shaft 20 is rotated, rods 14 ofthe pressing mechanism 12 rise in accordance with the rise of a rotatingglass rod 16 along the loci X and X' from the lower position during thenext half a second. At this time the rotating rod 16 contacts thearticles to be plated at the uppermost position to rotate the same. Whenhe crank shaft 20 makes one rotation and again causes a firm pressure onthe articles to be plated, the part to which current is supplied isvaried from that at the time of the previous plating.

An example of the plating process is described as follows: (when platingpieces of fasteners having a diameter of 9 mm a length of 52 mm).

The total plating time was 30 minutes and for the first 5 minutes afterthe start of plating a DC current of 0.5 a. was supplied, a cycle ofelectrolysis in a stationary state 16 sees. and rotating time 0.5 sec.was then repeated.

After then, a DC current of 4 a. was supplied after the first 5 minutesuntil 30 minutes since the start and a cycle of electrolysis in astationary state 63 secs. and rotating time 0.5 sec. was repeated.

0.8 a. of current was supplied to the supplemental anode during the last5 minutes of the plating time.

When current supply is started after the articles to be plated have beenrotated and then pressed against a cathode, it is preferable to decreasethe current to prevent the generation of sparks at the part to whichcurrent is supplied. It is also preferable to decrease the current inthe same manner when the supplying current is stopped to start therotation of the articles to be plated.

By using the novel apparatus for electroplating of the presentinvention, it is possible to perform the electroplating process highlyefficiently. Various effects obtained in accordance with the presentinvention are listed as follows:

(a) An accurate and sufficient supply of current to the articles to beplated is provided as the current is supplied when the articles to beplated are pressed on the cathodic conductor and in firm contact withthe same.

(b) It is possible easily to arrange a supplemental electrode for anindented part on an end and uniformly to plate even an inner surface ofsaid indented part as the plating process is carried out in a stationarystate.

(c) Traces partially beautifully or poorly electroplated due to pressuredo not stay on the articles to be plated as a plating process isperformed because of the variations of the part to which current issupplied at predetermined times.

(d) Excess current is not used except for plating and high efficiencycan be obtained as in a plating bath the specific part where current issupplied is in complete contact with the articles to be plated and otherparts are coated with insulation.

(e) A smooth operation is performed by intermittently activating bothpressing and rotating mechanisms, to vary and rotate the part to whichcurrent is supplied.

(f) Current is supplied through means such as a narrow electric wirecoated with Teflon to the articles to be plated, and said electric wirealso maintains the articles to be plated, so that current is notsupplied to parts with the exception of the articles to be plated. Thereis no obstacle in the vicinity of the articles to be plated, thusproviding a desirable condition for supplying of a plating solution andcurrent.

The aforementioned description is mainly concerned with fused saltaluminium electroplating. The present invention, however, is not limitedto the same, but is ap plicable to plating metals other than aluminiumin an aqueous solution.

What is claimed is:

1. An apparatus for electroplating in an electroplating bath,comprising:

cathode means on which may be supported a plurality ofcylindrically-shaped articles to be plated, parts of said cathode meansbeing shaped to receive said cylindrically-shaped articles,

an anode,

a rotating mechanism for varying the position of said articles so thatdifferent parts of said articles are brought into contact with saidcathode means,

a mechanism for pressing said articles to be plated against thecooperating parts of said cathode means during the time of currentsupply to said cathode means; and

control means for synchronizing the operation of said pressing mechanismand said rotaitng mechanism so that the pressing mechanism is inactivewhile the position of said articles is being changed.

2. An apparatus for electroplating in an electroplating bath,comprising:

cathode means on which may be mounted a plurality of articles to beplated,

an anode,

a mechanism for releasably pressing said articles to be plated againstthe surfaces of said cathode means, a rotating mechanism for varying theposition of said articles so that ditferent parts of said articles arebrought into contact with said cathode means,

means for controlling the supply of current to said cathode means,

means for synchronizing the operation of the pressing mechanism and therotating mechanism so that the pressing mechanism is inactive while theposition of said articles is being changed, and

means for interengaging the control means and the synchronizing means sothat supply of current is stopped upon activation of said rotatingmechanism.

3. Apparatus according to claim 1 wherein said cathode means includes aplurality of troughs for receiving said articles to be plated.

4. Apparatus according to claim 3 wherein each trough is partiallycovered with insulating material, there being an absence of insulatingmaterial at a part of a trough contacted by an article received therein.

5. Apparatus according to claim 1 wherein the pressing mechanismincludes a plurality of resilient rods, each rod having a part which isshaped and positioned to apply pressure to an article positioned forplating.

6. Apparatus according to claim 1 including means for controlling thesupply of current to said cathode means, and means for interengaging thesupply current control means and said synchronizing means so that supplyor current is stopped upon activation of said rotating mechanism.

7. Apparatus according to claim 2 including a supplemental anode adaptedto be located adjacent to the posi- 1 tion of one end of an article tobe plated when said article is supported on said cathode means.

8. Apparatus according to claim 2 wherein said cathode means includes aplurality of troughs for receiving said articles to be plated.

9. Apparatus according to claim 8 wherein each trough is partiallycovered with insulating material, there being an absence Off insulatingmaterial at a part of a trough contacted by an article received therein.

10. Apparatus according to claim 2 wherein the pressing mechanismincludes a plurality of resilient rods, each rod having a part which isshaped and positioned to apply pressure to an article positioned forplating.

References Cited UNITED STATES PATENTS 2,541,597 2/ 1951 Midling 204297R 3,133,007 5/1964 Creese et al. 204198 870,545 11/1907 Clough 204222FOREIGN PATENTS 1,582,692 10/ 1969 France 204231 JOHN H. MACK, PrimaryExaminer W. I. SOLOMON, Assistant Examiner US. Cl. X.R. 204297 R

